Aircraft: PA28
Phase of flight: Descent
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter CFTT / CFIT

On a night PIC cross country on which I was a passenger and Flight Instructor Not Flying; my student and I were descending into an airport for some pattern work. I had advised my student to deviate from his direct course in order to get around some lighted towers in the area during his descent and to stay at a safe altitude. I didn't notice that he'd descended to 1;900 feet until we were abeam some of the lighted towers; which in flight appeared to be more than 2;000 feet horizontally from the airplane. Even though we were equipped with a G1000 with an obstacle database; I had the engine page up since I wanted my student to use dead reckoning.Upon reexamination of our flight path after the flight; I realized we had missed the symbols on the sectional chart and flown through two fields of towers; some of which were unlit; and flew closer than 2;000 feet horizontally as well as less than 1;000 feet vertically to some of them. While flying over the second field of towers southeast of the field; we were descending to pattern altitude and setting up for landing. I believe the primary contributing factor; on my part; to be fatigue which caused me to zone in on the airport and miss my student's altitude drop and the symbology on the sectional. Descending down to land on a night cross country I saw a strip of asphalt with tightly spaced side lighting and took it to be the runways; so began a descent down from our cruising altitude. On our heading there are several tall towers that needed to be avoided; and I could identify them outside the plane on initial descent. My instructor was having me use pilotage for this leg; so I had no GPS or moving maps telling me exactly where I was. I passed the obstacles I had seen and visually confirmed them and was satisfied that we had maintained a 2;000 foot separation from all the obstacles. I believed they were the ones shown on the sectional chart. I continued to focus on what I believed to be the runway and continued down. About a minute after passing the obstacle I became aware that I had mistaken a large; then empty street with very bright lights to be the runway; but by this time we had come close to more obstacles. I believed myself to have been well over 2;000 feet of horizontal separation from these obstacles we were at 1;900 feet and performing what I thought was an approach to land; so I believed that we were okay and had avoided the obstacles satisfactorily.As said before; I became aware that what I thought was a runway was in fact a street and I began looking for the airport again; quickly finding it off about our 2 o'clock. I then proceeded with intent to enter a left base. I did that and landed safely. My flight instructor made me aware 5 days later that we had in fact broken obstacle clearances southeast of the airport. I was unaware that we had done that as I had both thought we had cleared them and I believed I had the runway in sight so I was descending to land. It appeared that I got too close to some obstacles that I could not see. It was night and they are not marked as lighted on the sectional chart. I saw some of the obstacles and thought I saw all of them. This; to the best of my knowledge; is what happened on this flight at about XA:30 am local time. I accidentally flew too close to some obstacles at night while descending down to what I believed to be the airport.I never saw them and was unaware that we even came close to any until my instructor told me 5 days later. The obstacles I saw and judged we were far enough away from were the only ones I assumed were there. In addition to solely relying on my eyes to find and avoid obstacles; I also was descending to land and trying to work out landing procedures and checklist items. The flight was also late so fatigue could have been a factor. Overall; I put more focus on trying to descend to the airport and land rather than making doubly sure that I had avoided all obstacles in the area with sufficient altitude. I am a fairly low hour pilot with little night time; so this serves as a valuable lesson to myself. I will now make sure my airplane is flying a route or I will identify a route that is completely and assertively safe from any hazards before beginning a descent down to the runway and I will now be paying extra attention to tall obstacles along my route of flight. A Flight Instructor and their student reported they flew too close to lighted tower when the student mistook a lit street for the airport.